Receiving and transporting apparatus for currency

ABSTRACT

A bill transport of a currency acceptor conveys a bill inserted thereinto along a path of travel having a sharp initial bend followed by a rectilinear stretch defined by an elongated, narrow channel. The bend is formed by rollers at the inside of the bend opposed by endless belts presenting the outside of the bend. A validity test station is located intermediate the ends of the cannel, and the bill is held flat as it is advanced along the channel by two rows of opposed pairs of rollers projecting into the channel and receiving the bill adjacent its longitudinal edges. A constant speed transport drive is provided by a direct current motor governed by a centrifugal chopper. Failure to maintain proper operating speed due to jamming or the like results in the application of an unchopped voltage to the motor, causing voltage to build up across a capacitor to a level which fires a programmable unijunction transistor that, through associated switching circuits, reverses the polarity at the motor input connections to reverse the drive and return the bill to the insert opening. Such switching circuits are also operated by the validity tester to return a bill found to be invalid.

United States Patent Ptacek [151 3,656,615 [451 Apr. 18, 1972 [54] RECEIVING AND TRANSPORTING APPARATUS FORCURRENCY [72] Inventor: James F. Ptacek, Kansas City, Mo. [73] Assignee: The Vendo Company, Kansas City, Mo.

[22] Filed: Oct. 9, 1970 [2 l] Appl. No.: 79,456

[52] U.S. Cl 209/73, 209/74, 226/25, 271/57 [5 l] Int. Cl. B07c 3/02 [58] Field of Search ..209/73, DIG. 2, 75, 74; l 226/25; 271/47, 57, DIG. 9

[56] References Cited UNITED sTATEs PATENTS 3,114,902 l2/l963 Tanguy ..27l/57-X 3,485,358 12/1969y Hooker ..209/75X Primaryl Examiner-Richard A. Schacher Attorney-Schmidt, Johnson, Hovey, Williams & Chase [571 ABSTRACT A bill transport of a currency acceptor conveys a bill inserted thereinto along a path of travel having a sharp initial bend followedby a rectilinear stretch defined by an elongated, narrow channel. The bend is formed by rollers at the inside of the bend opposed by endless belts presenting the outside of the bend. A validity test station is located intermediate the ends of the cannel, and the bill is held flat as it is advanced along the channel by two rows of opposed pairs of rollers projecting into the channel and receiving the bill adjacent its longitudinal edges. A constant speed transport drive is provided by a direct current motor governed by a centrifugal chopper. Failure to maintain proper operating speed due to jamming or the like results in the application of an unchopped voltage to the motor, causing voltage to build up across a capacitor to a level which fires a programmable unijunction transistor that,

, through associated switching circuits, reverses the polarity at the motor input connections to reverse the drive and return the bill to the insert opening. Such switching circuits are also operated by the validity tester to return a bill found to be in valid. l

18 Claims, 6 Drawing Figures PATENTEUAPR 18 |972 SHEU l UF 2 /NVEN'IUR James F. Pfacek ATTORNEYS.

PATENTEUAPR 18 |912 SHEET 2 UF 2 James HTTORNEYS.

IIL VIL IL VA. Q Qx n Z .N l,

RECEIVING AND TRANSPORTING APPARATUS FOR CURRENCY CROSS-REFERENCES See my concurrently tiled copending application, Ser. No. 79,444 filed Oct. 9, 1970, entitled Currency Testing System, and the copending application of Boley A. Andrews and James F. Ptacek, Ser. No. 886,530, filed Dec. I9, 1969, and entitled Combined Optical and Magnetic Transducer.

This invention relates to improvements in bill transporting apparatus utilized in currency acceptors or validators.

It is an important object of the present invention to provide a compact and easily serviceable currency acceptor for vending machines, bill changers and the like, and to therefore provide a bill transport of relatively uncomplex mechanical design capable of conveying the bill under test in a flat disposition and at constant speed along a rectilinear path of travel past the test station for validity determination.

Another important object of this invention is to provide a bill transport as aforesaid which causes the bill to follow a total path of travel from insertion to acceptance that is arranged to maximize the compactness of the acceptor while still facilitating the servicing thereof.

Stillfnother important object of the invention is to provide a currency acceptor wherein the transport drive thereof immediately reverses to return the deposited bill in the event of an overload condition such as might be caused by jamming or failure of the depositor to quickly release the bill, as well as in the event that the bill is determined to be invalid.

Furthermore, it is an important objectof the invention to provide control circuitry for a bill transport which maintains an electric drive motor for the transport at a substantially constant operating speed, and which is capable of electrically sensing a decrease in such speed indicative of an overload and effecting reversal of the motor in response thereto.

In the drawings:

FIG. l is a side elevational view ofthe acceptor unit of the present invention;

FIG. 2 is a rear elevational view of the unit showing the same with the electronics module removed therefrom;

FIG. 3 is a front view of the electronics module as seen removed from the acceptor unit;

FIG. 4 is a vertical sectional view taken along line 4--4 of FIG. 2;

FIG. 5 isa front view of the unit on a reduced scale, a cabinet wall on` which the unit is mounted being shown fragmentarily; and

FIG. 6 is an electrical schematic diagram showing control circuitry for the drive motor of the bill transport.

Referring initially to FIGS. 1-5, the currency acceptor is broadly denoted by thenumeral l0 and has a housing that includes a pair of spaced sidewalls l2 and a front panel 14, the acceptor 10 being shown in FIG. 5 as it would appear mounted on a wall 16 of the cabinet of a vending machine, bill changer or the like. Approximately the lower half of the front panel 14 slopes inwardly to, in cooperation with an upwardly extending ramp 18, present an insert opening 20 for receiving a bill. In FIG. 4, a bill to be tested bythe acceptor is illustrated at 22 shortly after advancement thereof into the acceptor is commenced by a bill transport 24 to be subsequently described in detail.

The drive components of the bill transport 24 are shown in FIGS. l, 2 and 4. The acceptor housing is provided with a backplate 26 which is elongated and steeply inclined, the upper end of the backplate 26 being rounded to smoothly merge with the rounded upper end of the ramp 18. Four rotatable shafts 28, 30, 32 and 34 are vertically spaced in front of the backplate 26 and extend horizontally between the sidewalls l2. Referring first to the uppermost shaft 28, a pair of friction rollers 36 are rigid with shaft 28 and spaced apartso as to be located adjacent respective sidewalls l2 as is clear in FIG. 2. Clearance openings are provided in the backplate 26 and the ramp 18 to permit the circumferential, frictional surfaces ofthe rollers 36 to extend through both the backplate 26 and the ramp 18 for a purpose to be discussed hereinafter. In similar fashion, a pair of friction rollers 38 rotate with shaft 30, a pair of friction rollers 40 are provided on the shaft 32, and the lowermost shaft34 is likewise provided with a pair of friction rollers 42. As is clear in FIG. 2, two rows of rollers are presented, each of which is adjacent a corresponding sidewall 12. A's will be appreciated hereinafter, the rollers 36-42 are thus disposed adjacent the longitudinal edges of a bill being conveyed by the transport 24.

The left ends of the rotatable shafts 28-34 project from the left sidewall 12 as viewed in FIG. 2 and are provided with pulleys 44, 46, 48 and 50 respectively. A drive motor 52 is located behind the panel 14 (together with associated power supply components which are not illustrated) and has an output shaft 54 providedwith a drive pulley 56. A stationary cross shaft 58 extends horizontally between the sidewalls l2 just be` hind the lower end portion of the front panel 14, the cross shaft 58 serving to rotatably mount a reduction pulley 60 driven by a belt 62 trained around the drive pulley 56 and a larger diameter section of the reduction pulley 60. A second belt 64 is then trained around a smaller diameter section of the pulley 60, an idler 66, pulleys 44 and 46, and idler 68, and pulleys 48 and 50.v Since the pulleys 44-50 are of the same size, it is apparent that the rollers 36-42 (all of equal diameter) are driven simultaneously in the same direction at the same speed.

A pair of horizontally spaced, generally J-shaped side plates 70 support a J-shaped guide plate 72 therebetween which defines the general outline of a sharp bend in the path of travel of the bill 22. More particularly, a top roll 74 extends horizontally between the side plates 70 and is rotatably supported thereby. A pair of pulleys 76 are located forwardly and downwardly from the roll 74 and are interconnected for rotation in unison about a horizontal axis. Likewise, a pair of pulleys 78 are spaced directly below the top roll 74 and also rotate in unison about a horizontal axis. A pair of endless belts 80 are trained around the roll 74 and respective pulleys 76 and 78 as is clear from a comparison of FIGS. 2 and 4. The stretches of the belts 80 between the pulleys 76 and 78 are held against the friction rollers 36 thereby presenting a nip for receiving the leading edge of the bill 22 upon insertion of the latter into the opening 20. In this regard, note that a slot 82 is defined between the guide plate 72 and the upper end portion of the ramp 18 for the purpose of guiding the leading edge of rthe bill 22 into the nip formed by the opposed rollers 36 and belts 80. 4-

From the foregoing, it may be appreciated that the roll 74,

pulleys 76 and 78, and belts 80 fonn a corner assembly which cooperates with the rollers 36 to define a sharp bend in the pathv to be travelled by the bill 22. The entire assembly may be removed as a unit to facilitate servicing, thus the lower, forward ends of the side plates 70 may be slotted as shown to receive the cross shaft 58 and thereby key the assembly into its proper position. A small electric lamp 84 is disposed between the side plates 70, and the guide plate 72 has an aperture 86 to pennit light to be directed from the lamp 84 toward an opening 88 inthe ramp 18 and a corresponding opening 90 in the backplate 26.

An electronics module 92 includes an elongated, channelshaped support plate 94 for the circuit board thereof and other electrical and mechanical components to be described. Four lugs 96 project from the sides of the support plate 94 and are received by brackets 98 to mount the module 92 with the front face 100 of the support plate 94 in closely spaced, parallel relationship with the backplate 26. Accordingly, the opposed, planar faces ofthe closely spaced plates define an elongated, narrow channel 102 into which the bill is fed after traversing the bend described hereinabove. The module 92 is held in the brackets 98 by a latch 104 associated with one of the brackets 98, thus the module 92 may be readily detached from the acceptor unit for servicing or to facilitate cleaning of the surfaces in the channel 102 subject to continual contact by transported bills.

As is clear in FIGS. 3 and 4, a pair of idler rollers 106 project through clearance openings in support plate 94 and engage corresponding friction rollers 38. Likewise, a pair of idler rollers 108 and a pair of idler rollers 110 engage friction rollers 40 and 42 respectively. Accordingly, the bill traversing the channel 102 will be sandwiched between each friction roller and its opposing idler roller. A test station is provided intermediate the ends of the channel 102 as illustrated by the transducer head 112 projecting through the front face 100 of the support plate 94, and the electric lamp 114 opposing the head 112 and carried by the backplate 26. The head 112 shown herein is a combined optical and magnetic transducer as disclosed in the above-identified application of Boley A. Andrews and James F. Ptacek, Ser. No. 886,530, but other means of sensing the physical properties of the bill may be employed as appropriate to the particular validity testing system embodied in the electronics of the module 92. A suitable testing system is disclosed in my above-identified copending application, Ser. No. 79,444, wherein input information in the system logic includes sensing the presence of the leading edge of the bill upon insertion into the slot 82 and sensing such leading edge again at the lower end ofthe channel 102. To this end, a phototransistor 116 in the module 92 is disposed to receive light emanating from the lamp 84, and a phototransistor 118 is positioned to receive light emanating from an electric lamp 120 at the lower end of the channel 102.

Referring to FIG. 6, the motor 52 is illustrated schematically together with its output shaft 54. The motor 52 is of the reversible, direct current type and has a pair of input connections 122 across which a direct voltage is applied. The leads labeled +24 V and -24 V represent power leads from a 24 volt DC supply comprising the power source for the motor 52. The control circuitry is operated at lower voltage levels as indicated by the supply leads labelled V and -l5 V.

A governor is provided by a centrifugal contact 124 which rotates with the motor shaft 54. The contact 124 is in the nature of a normally closed switch which opens under centrifugal force when the shaft 54 exceeds a predetermined operating speed. The switch 124 is serially connected in a lead 126 which branches at 128 and is connected to the base of an NPN emitter follower transistor 130. A second branch 132 extends to the base of a PNP transistor 134 which is also operated as an emitter follower. The collectors of the transistors 130 and 134 are connected to the +24 V and -24 V leads respectively, and their emitters are connected to the upper input connection 122 of the motor 52. The lower input connection 122 is at circuit ground as indicated by the symbol.

A lead 136 extends from the upper input connection 122 to a resistor 138 that is in series with a trigger capacitor 140. The lead 136 and resistor 138 constitute a charging circuit to the capacitor 140, the latter being connected in parallel with a programmable unijunction transistor 142 and a series cathode resistor 144. Both the lower end of the resistor 144 and the lower plate of the capacitor 140 are at ground potential.

A resistor 146 and a series diode 148 are connected from the upper plate of the capacitor 140 to the lead 136 and present a discharge path for the capacitor 140, the resistance of the resistor 146 being substantially less than the resistance of the resistor 138. A series connected diode 150 and capacitor 152 are connected across the capacitor 140, and a resistor 154 is connected in parallel with thecapacitor 152.

A silicon controlled rectifier 156 has its gate directly connected to the cathode of the PUT 142, and a lead 158 extends to the gate of the SCR 156 from the validator circuitry represented by the block 160 having the legend validity tester. The function of the SCR 156, upon triggering thereof, is to reverse the drive to the transport 24 to return a deposited bill to the insert opening 20, either in response to an overload condition (to be discussed) or a determination by the validity tester 160 that the bill is invalid. The SCR 156 is coupled with switching circuitry including three PNP switching transistors 162, 164 and 166 having their emitters connected to the +15 volt power lead, and a NPN switching transistor 168 having its emitter connected to the l5 volt power lead. A normally open switch 170 through a resistor 172 connects the base of the transistor 164 and the collector of the transistor 166 to ground upon closure thereof, and is diagrammatically illustrated as operated by the validity tester 160. The lead 126 to the governor switch 124 is connected to the collector of the transistor 164 via resistor 174, and to the collector of the transistor 168 via resistor 176. A reset lead is shown at 178 conited to the anode of the SCR 156 by a coupling capacitor OPERATION A bill, such as indicated at 22 in FIG. 4, is placed in the insert opening 20 and its leading edge is manually fed into the slot 82. The proper disposition of the bill 22 may be indicated to the depositor by providing the surface of the ramp 18 with a properly oriented facsimile of the bill (not shown). When the bill has been inserted sufficiently to cover the opening 88 and thereby block the light normally impinging on the phototransistor-116, the validity tester 160 commences operation of the transport 24, such action being represented in FIG. 6 by the closure of switch 170. The switching transistor 164 now conducts and positive voltage is made available on lead 126. This places the emitter follower transistor in conduction to thereby supply the motor 52 with positive voltage at its upper input connection 122. This is the forward drive condition. At this time switching transistors 162, 166 and 168 are nonconducting.

It may be appreciated that the bill 22 immediately traverses a sharp bend around the two rollers 36 defining the inside of such bend. The outside of the bend is presented by the two endless belts 80, the bill 22 being received in the nip presented by the rollers 36 and opposing belts 80. As the leading edge of the bill 22 passes the bend as depicted in FIG. 4, it enters a rectilinear stretch defined by the narrow channel 102. Those portions of the bill 22 in the channel 102 remain flat due to the confines of the narrow channel and the nature of the drive therein. In this respect, it should be noted that the opposed rollers 38 and 106 are adjacent the longitudinal edges of the bill as are the later roller pairs 40, 108 and 42, 110. With all of the rollers 38, 40 and 42 being driven at the same speed, drive is applied to the bill without causing bunching or otherwise significantly distorting the bill from a flat orientation along a rectilinear course. Accordingly, the bill is essentially flat and straight as it passes the test station and is sensed by the head 112. From the input infonnation derived from the head 112, a validity determination is made and, if the bill is found valid, the transport drive is not disturbed. This results in ultimate acceptance of the bill as it emanates from the lower end of the channel 102 and passes into a suitable receptacle (not shown). If the bill is found to be invalid, a reject pulse appears along lead 158 to trigger the SCR 156, causing reversal of the transport drive in a manner to be subsequently explained.

When the SCR 156 is placed in conduction, the bases of the switching transistors 162 and 166 go negative with respect to the emitters thereof, thereby placing transistors 162 and 166 in conduction and turning oli` the transistor 164. A voltage divider is formed by a pair of series connected resistors 182 and 184 connected between the collector of transistor 162 and the -15 volt supply lead. Since the base of transistor 168 is connected to the common connection of the resistors 182 and 184, such base goes positive with respect to the emitter of transistor 168 to render the same conductive. Accordingly, in stead of being connected through transistor 164 to the +15 volt supply lead, the lead 126 is now connected to the -15 volt supply lead through the transistor 168. Therefore, emitter follower 134 now conducts instead of emitter follower 130 thereby applying negative voltage to the upper input connection 122 of the motor 52. With the transport drive now reversed, the bill is returned to the opening 20, whereupon the motor control circuitry is reset by a negative voltage applied to reset lead 178 by the validity tester logic. The negative reset pulse appearing at the anode of the SCR 156 momentarily interrupts current flow therethrough to effect the resetting funcv waveform illustrated at 186 for the forward operating direction. Note the notches 188 caused by the chopping action and occurring during times that the switch 124 is open.

As long as the chopped waveform 186 is supplied to the motor 52, the capacitor 140 alternately charges and discharges. However, in the event that an overload condition should occur in the transport drive, such as by jamming ofthe bill or failure ofthe depositor to quickly release the bill once it is pulled onto the transport drive, the speed of the shaft 54 decreases and normal operating speed is not maintained. Under such condition the switch 124 remains closed and the voltage is no longer chopped, thus voltage is permitted to build up across the capacitor 140 until the ring potential of the PUT 142 is reached. When the PUT 142 conducts, the SCR 156 is triggered by the voltage drop across resistor 144. This immediately `causes reversal of the transport drive as in the previous case where the bill was found to be invalid. Once the bill is returned to the insert opening 20, the circuitry is reset as before.

From the foregoing, it may be appreciated that the speed at which the bill is advanced by the transport 24 is maintained constant to facilitate accurate sensing of the physical properties of the bill by the head 112 at the test station. Currency testing systems commonly respond to lines of magnetic ink appearing on the bill, thus constant bill speed is important if the spacing between such lines is to be ascertained by a frequency responsive system. ln thepresent invention a test will not be run other than at the preselected bill speed, since greater speeds are prevented by the governor action and lesser speeds cause the bill to be returned to the depositor. l

Manifestly, the speed test that is performed as discussed above must be delayed until the motor shaft 54 has an opportunity to reach operating speed. Accordingly, the capacitor 152 is provided and charges during thestart-up voltage surge to prevent triggering of the PUT 142 ancll delay the speed test in accordance with the RC time constant of capacitor 152 and resistor 154.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

l. ln a currency acceptor:

means presenting an insert opening for receiving a bill to be tested;

a transport adjacent said opening for conveying an inserted bill along a path of travel having a substantially rectilinear stretch,

said transport being provided with structure for holding the bill flat during movement thereof through said stretch;

a test station intermediate opposed ends of said stretch having means for sensing physical properties of the bill as it traverses said stretch;

power means coupled -with said transport for driving the latter at a substantially constant speed as the bill is con.- veyed through said stretch past said station for testing; and

control and validity deterrnning means operably coupled with said bill sensing means and said power means for reversing the drive to the transport to return the bill to said insert opening either in response to a decrease in the speed of the transport indicative of an overload condition, or if the bill is invalid.

2. ln a currency acceptor as claimed in claim l,

said structure presenting a narrow channel defrning said stretch, and having rotatable means projecting into said channel for frictional engagement with the bill, said power means being connected with said rotatable means for rotating the latter to advance the bill along said channel.- 3. In a currency acceptor as claimed in claim l, said'structure presenting a narrow channel defining said stretch, and having opposed pairs of rollers projecting into said channel for frictionally engaging the bill therebetween, said power means being connected with one roller of each of said pairs thereof for simultaneously rotating the same to advance the bill along said channel. 4. lna currency acceptor as claimed in claim 3, said channel being elongated in the direction of advancement of the bill therealong, said pairs of rollers being arranged in two rows adjacent respective longitudinal edges of the bill as it is advanced along said channel, the roller pairs of each row being spaced apart longitudinally of said channel. 5. ln a currency acceptor as claimed in claim l, said transport having comer means presenting a bend in said path between said insert opening and said stretch, said comer means including a roller member at the inside of said bend and an endless belt member trained over said roller member t'o present the outside of said bend, said members being disposed to frictionally receive the bill therebetween, said power means being connected with one of said members tol drive the latter and thereby advance the bill around the bend. 6. In a currency acceptor as claimed in claim 5, said members presenting a bill-receiving nip adjacent said insert opening, there being a slot communicating said opening with said nip to permit feeding ofthe bill to the nip. 7. ln a currency acceptor as claimed in claim 1, said power means including an electric motor having an output shaft, said control and validity determining means including means responsive to said motor for sensing the speed of said shaft', and circuitry coupled with said speed sensing means and said motor for effecting a reversal of the direction of rotation of said shaft when the speed thereof falls below a predetermined operating speed. 8. ln a currency acceptor as claimed in claim l, said power means including an electric motor having electrical input connections and an output shaft, said control and validity determining means including switch means responsive to said motor and operable to change from a normal condition to an operated condition when the speed of said shaft exceeds a predetermined operating speed, and circuitry coupled with said input connections and said switch means for applying voltage to said input connections, and said voltage having a chopped characteristic in response to changes in the condition of said switch means, whereby to maintain the shaft at substantially said predetermined operating speed to thereby drive the transport and convey the bill at substantially constant speed. 9. In a currency acceptor as claimed in claim 8, said circuitry having means responsive to said voltage for ef fecting a reversal of the direction of rotation of said shaft when the speed thereof falls below said predetermined operating speed. 10. In a currency acceptor as claimed in claim 8, said motor being sensitive to the polarity of the voltage applied to said input connections thereof, Said circuitry having a trigger capacitor, a charging circuit for said capacitor coupled with said input connections, and electrically responsive switching means coupled with said capacitor and responsive to a predetermined buildup of voltage thereacross for reversing the polarity of the voltage applied to said input connections, whereby the y motor is reversed unless the voltage supplied thereto continues to be chopped.

11. ln a currency acceptor:

means presenting an insert opening for receiving a bill to be tested;

a transport adjacent said opening for conveying an inserted bill along a path of travel having a substantially rectilinear stretch,

said transport being provided with structure for holding the bill flat during movement thereof through said stretch,

said structure presenting an elongated, narrow channel defining said stretch, and having rotatable means projecting into said channel for frictional engagement with the bill;

a test station intermediate opposed ends of said channel having means for sensing physical properties of the bill as it traverses said channel; and

power means coupled with said rotatable means for driving the latter at a substantially constant speed to advance the bill along said channel past said station for testing, said transport having comer means presenting a bend in said path between said insert opening and said channel,

said corner means including a roller member at the inside of said bend and an endless belt member trained over said roller member to present the outside of said bend,

said members being disposed to frictionally receive the bill therebetween,

said power means being connected with one of said members to drive the latter and thereby advance the bill around the bend.

l2. ln a currency acceptor as claimed in claim 11,

said rotatable means comprising opposed pairs of rollers for frictionally engaging the bill therebetween,

said power means being connected with one roller of each of said pairs thereof` for simultaneously rotating the same.

13. In a currency acceptor as claimed in claim 12,

said pairs of rollers being arranged in two rows adjacent respective longitudinal edges of the bill as it is advanced along said channel,

the roller pairs of each row being spaced apart longitudinally of said channel.

14. ln a currency acceptor as claimed in claim 11,

said members presenting a bill-receiving nip adjacent said insert opening,

there being a slot communicating said opening with said nip to permit feeding ofthe bill to the nip.

. l5. ln a currency acceptor:

means presenting an insert opening for receiving a bill to be tested;

a transport adjacent said opening for conveying an inserted bill along a path of travel within the acceptor;

a test station adjacent said path having means for sensing physical properties of the bill as it travels along said path;

an electric motor having electrical input connections and an output shaft mechanically coupled with said transport for driving the latter to advance the bill past said station for testing;

means responsive to said motor for sensing the speed of said shaft; and

circuitry coupled with said input connections and said speed sensing means for effecting a reversal of the direction of rotation of said shaft when the speed thereof falls below a predetermined operating speed, whereby to return the bill tol said insert opening in the event of an overload or the like.

16. ln a currency acceptor as claimed in claim l5,

said speed sensing means comprising switch means operable to change from a normal condition to an operated condition when the speed of said shaft exceeds said predetermined operatin speed, l said circui ry app ymg voltage to said mput connections of the motor, and said voltage having a chopped characteristic in response to changes in the condition of said switch means, whereby to maintain said shaft at substantially said predetermined operating speed to thereby drive the transport and advance the bill at substantially constant speed.

17. ln a currency acceptor as claimed in claim 16,

said circuitry having means responsive to said voltage for effecting said reversal of the direction of rotation of said shaft when the speed thereof falls below said predetermined operating speed.

18. ln a currency acceptor as claimed in claim 16,

said motor being sensitive to the polarity of the voltage applied to said input connections thereof,

said circuitry having a trigger capacitor, a charging circuit for said capacitor coupled with said input connections, and electrically responsive switching means coupled with said capacitor and responsive to a predetermined buildup of voltage thereacross for reversing the polarity of the voltage applied to said input connections, whereby to reverse the motor to effect said reversal of the direction of rotation of said shaft unless the voltage supplied to the motor continues to be chopped. 

1. In a currency acceptor: means presenting an insert opening for receiving a bill to be tested; a transport adjacent said opening for conveying an inserted bill along a path of travel having a substantially rectilinear stretch, said transport being provided with structure for holding the bill flat during movement thereof through said stretch; a test station intermediate opposed ends of said stretch having means for sensing physical properties of the bill as it traverses said stretch; power means coupled with said transport for driving the latter at a substantially constant speed as the bill is conveyed through said stretch past said station for testing; and control and validity determining means operably coupled with said bill sensing means and said power means for reversing the drive to the transport to return the bill to said insert opening either in response to a decrease in the speed of the transport indicative of an overload condition, or if the bill is invalid.
 2. In a currency acceptor as claimed in claim 1, said structure presenting a narrow channel defining said stretch, and having rotatable means projecting into said channel for frictional engagement with the bill, said power means being connected with said rotatable means for rotating the latter to advance the bill along said channel.
 3. In a currency acceptor as claimed in claim 1, said structure presenting a narrow channel defining said stretch, and having opposed pairs of rollers projecting into said channel for frictionally engaging the bill therebetween, said power means being connected with one roller of each of said pairs thereof for simultaneously rotating the same to advance the bill along said channel.
 4. In a currency acceptor as claimed in claim 3, said channel being elongated in the direction of advancement of the bill therealong, said pairs of rollers being arranged in two rows adjacent respective longitudinal edges of the bill as it is advanced along said channel, the roller pairs of each row being spaced apart longitudinally of said channel.
 5. In a currency acceptor as claimed in claim 1, said transport having corner means presenting a bend in said patH between said insert opening and said stretch, said corner means including a roller member at the inside of said bend and an endless belt member trained over said roller member to present the outside of said bend, said members being disposed to frictionally receive the bill therebetween, said power means being connected with one of said members to drive the latter and thereby advance the bill around the bend.
 6. In a currency acceptor as claimed in claim 5, said members presenting a bill-receiving nip adjacent said insert opening, there being a slot communicating said opening with said nip to permit feeding of the bill to the nip.
 7. In a currency acceptor as claimed in claim 1, said power means including an electric motor having an output shaft, said control and validity determining means including means responsive to said motor for sensing the speed of said shaft, and circuitry coupled with said speed sensing means and said motor for effecting a reversal of the direction of rotation of said shaft when the speed thereof falls below a predetermined operating speed.
 8. In a currency acceptor as claimed in claim 1, said power means including an electric motor having electrical input connections and an output shaft, said control and validity determining means including switch means responsive to said motor and operable to change from a normal condition to an operated condition when the speed of said shaft exceeds a predetermined operating speed, and circuitry coupled with said input connections and said switch means for applying voltage to said input connections, and said voltage having a chopped characteristic in response to changes in the condition of said switch means, whereby to maintain the shaft at substantially said predetermined operating speed to thereby drive the transport and convey the bill at substantially constant speed.
 9. In a currency acceptor as claimed in claim 8, said circuitry having means responsive to said voltage for effecting a reversal of the direction of rotation of said shaft when the speed thereof falls below said predetermined operating speed.
 10. In a currency acceptor as claimed in claim 8, said motor being sensitive to the polarity of the voltage applied to said input connections thereof, said circuitry having a trigger capacitor, a charging circuit for said capacitor coupled with said input connections, and electrically responsive switching means coupled with said capacitor and responsive to a predetermined build-up of voltage thereacross for reversing the polarity of the voltage applied to said input connections, whereby the motor is reversed unless the voltage supplied thereto continues to be chopped.
 11. In a currency acceptor: means presenting an insert opening for receiving a bill to be tested; a transport adjacent said opening for conveying an inserted bill along a path of travel having a substantially rectilinear stretch, said transport being provided with structure for holding the bill flat during movement thereof through said stretch, said structure presenting an elongated, narrow channel defining said stretch, and having rotatable means projecting into said channel for frictional engagement with the bill; a test station intermediate opposed ends of said channel having means for sensing physical properties of the bill as it traverses said channel; and power means coupled with said rotatable means for driving the latter at a substantially constant speed to advance the bill along said channel past said station for testing, said transport having corner means presenting a bend in said path between said insert opening and said channel, said corner means including a roller member at the inside of said bend and an endless belt member trained over said roller member to present the outside of said bend, said members being disposed to frictionally receive the bill therebetween, said power means being connected with one of said members to drive the latter and thereby advance the bill around the bend.
 12. In a currency acceptor as claimed in claim 11, said rotatable means comprising opposed pairs of rollers for frictionally engaging the bill therebetween, said power means being connected with one roller of each of said pairs thereof for simultaneously rotating the same.
 13. In a currency acceptor as claimed in claim 12, said pairs of rollers being arranged in two rows adjacent respective longitudinal edges of the bill as it is advanced along said channel, the roller pairs of each row being spaced apart longitudinally of said channel.
 14. In a currency acceptor as claimed in claim 11, said members presenting a bill-receiving nip adjacent said insert opening, there being a slot communicating said opening with said nip to permit feeding of the bill to the nip.
 15. In a currency acceptor: means presenting an insert opening for receiving a bill to be tested; a transport adjacent said opening for conveying an inserted bill along a path of travel within the acceptor; a test station adjacent said path having means for sensing physical properties of the bill as it travels along said path; an electric motor having electrical input connections and an output shaft mechanically coupled with said transport for driving the latter to advance the bill past said station for testing; means responsive to said motor for sensing the speed of said shaft; and circuitry coupled with said input connections and said speed sensing means for effecting a reversal of the direction of rotation of said shaft when the speed thereof falls below a predetermined operating speed, whereby to return the bill to said insert opening in the event of an overload or the like.
 16. In a currency acceptor as claimed in claim 15, said speed sensing means comprising switch means operable to change from a normal condition to an operated condition when the speed of said shaft exceeds said predetermined operating speed, said circuitry applying voltage to said input connections of the motor, and said voltage having a chopped characteristic in response to changes in the condition of said switch means, whereby to maintain said shaft at substantially said predetermined operating speed to thereby drive the transport and advance the bill at substantially constant speed.
 17. In a currency acceptor as claimed in claim 16, said circuitry having means responsive to said voltage for effecting said reversal of the direction of rotation of said shaft when the speed thereof falls below said predetermined operating speed.
 18. In a currency acceptor as claimed in claim 16, said motor being sensitive to the polarity of the voltage applied to said input connections thereof, said circuitry having a trigger capacitor, a charging circuit for said capacitor coupled with said input connections, and electrically responsive switching means coupled with said capacitor and responsive to a predetermined build-up of voltage thereacross for reversing the polarity of the voltage applied to said input connections, whereby to reverse the motor to effect said reversal of the direction of rotation of said shaft unless the voltage supplied to the motor continues to be chopped. 